From the prior art it is known to cut-up oven-ready poultry carcasses with an installation having a feed conveyor and multiple cut-up lines to which carcasses are supplied by said feed conveyor.
The provision of multiple cut-up lines is primarily done as the carcasses that have to be processed on the cut-up lines have different sizes. In order to obtain optimal results from the cut-up line processing, it is common to have each cut-up line set up for a specific range of carcass size so that the cutting actions performed by the one or more cutting devices of each line yield optimal results. It is known that some poultry cutting devices even allow for real-time automatic adjustment of the one or more cutting tools, yet even their performance is enhanced if the carcass size lies within a specific range.
The carcasses are conveyed by the feed conveyor whilst being suspended from their legs, each carrier of the feed conveyor supporting a single carcass. Also the conveyor of each of the cut-up lines is embodied such that a carrier thereof supports a single carcass that is suspended by its legs from the carrier. For each cut-up line a transfer device, often embodied as a rotary overhanger device, is provided, that transfers a carcass from the feed conveyor carrier to a cut-up line conveyor carrier.
It is known from the prior art to provide in such an installation a weigher that weighs each individual carcass. As weight of the carcass is commonly considered to be fairly representative of the size of the carcass it is known to provide the installation with a computerized production control system that allocates each of the oven-ready carcasses to a specific cut-up line on the basis of the weight of the oven-ready carcass.
Examples of this prior art approach are disclosed in U.S. Pat. No. 4,813,101 and U.S. Pat. No. 5,453,045.
In U.S. Pat. No. 5,326,311 it is disclosed that the grading of the oven-ready carcasses in view of their grading into a category and resulting allocation to a specific cut-up line can be performed on the basis of a determination of the individual carcass size by an imaging device, possibly in combination with a determination of the carcass weight. The imaging device may be embodied to determine one or more dimensions of the carcass, the shape or contour of the carcass, etc.
In U.S. Pat. No. 5,326,311 a poultry processing installation is discussed that has three parallel cut-up lines; one set up for small size carcasses, one set up for intermediate size carcasses, and one set up for large size carcasses. Whilst the provision of three cut-up lines, each set for a different carcass size category, in an installation may be beneficial in view of the results of the cut-up processing of the carcasses, many (potential) poultry plant owners are reluctant to acquire such an installation due to the associated investment and operating costs.
It is therefore more common that an installation of this type has only two cut-up lines, wherein the one cut-up line is set up to process relatively small carcasses, whereas the other cut-up line is commonly set up to process relative large carcasses.
U.S. Pat. No. 4,483,047 discloses an installation with two cut-up lines, wherein a computerized control system grades each of the weighed carcasses conveyed by the feed conveyor into one of two categories:                a lightweight category if the weight of said carcass is below a weight limit,        a heavyweight category if the weight of said carcass is above this weight limit.        
In this known embodiment the carcasses in the lightweight category are transferred from the feed conveyor to the first cut-up line conveyor, and the carcasses in the heavyweight category are transferred from the feed conveyor to the second cut-up line conveyor.
Again in view of the associated investment and operating costs, it is common for poultry processing installations with two cut-up lines that the combined carcass processing capacity of the two cut-up lines is equal or only slightly greater than the capacity of the feed conveyor such as to avoid undue idling of cut-up lines.
In some embodiments known transfer devices used for transferring carcasses to cut-up lines provide a buffer for a limited number of carcasses, commonly between 4 and 10 buffer positions, to temporarily buffer carcasses in the transition between the feed conveyor and the cut-up line conveyor. An example is disclosed in U.S. Pat. No. 7,837,540.
In practice, when operating a two cut-up lines installation, it is observed that quite frequently during the processing of a flock of birds, the situation arises that the capacity of the combination of a transfer device, even when provided with a buffer, and the associated cut-up line is—at least temporarily—insufficient to receive all the carcasses of the respective category. This is then signalled to an operator person who can then decide to either have carcasses re-allocated to the other category and then processed at the other cut-up line, or to discharge a number of carcasses from the feed conveyor, e.g. at a discharge station. This entails a reduction of quality and/or yield of the processed carcasses, may require (manual) reworking of carcass parts, and cause an undesirable burden on the operator person.